Drug therapy persistence and stroke recurrence

Objective: To assess the effect of persistence of use of warfarin sodium, aspirin, or clopidogrel bisulfate on stroke recurrence in a Medicaid high-risk, largely female, African American population. Study Design: Prospective nonconcurrent cohort, longitudinal data analysis of medical and pharmacy claims of stroke patients from Medicaid managed care organizations between January 1, 2001, and December 31, 2003. Methods: Cox proportional hazards models were used to predict the likelihood of avoiding a recurrence as a function of persistence of use of the initial medication (warfarin, aspirin, or clopidogrel) after stroke, adjusting for age, race, sex, hypertension and other comorbidities, and the pharmacotherapies prescribed. We used propensity scores to adjust for confounding by indication. Results: Among 925 stroke patients (64.6% female, 75.1% ≥50 years, and 57.8% African American), hypertension and heart disease were the most prevalent comorbidities (66.1% and 65.1%, respectively); most initial strokes were nonhemorrhagic. Persistence of use of warfarin, aspirin, or clopidogrel after stroke increased the likelihood of avoiding a recurrence (hazard ratio [HR], 1.57; 95% confidence interval [CI], 1.22-2.01). Having a hemorrhagic stroke initially (HR, 0.37; 95% CI, 0.18-0.74) or having heart disease (HR, 0.82; 95% CI, 0.67-1.01), hypertension (HR, 0.63; 95% CI, 0.51-0.79), or diabetes mellitus (HR, 0.74; 95% CI, 0.60-0.91) after an initial stroke significantly decreased the likelihood of avoiding a recurrence. Patient's age, race, sex, and urban residence did not significantly predict the likelihood of avoiding a recurrence. Conclusions: Persistence of use of the initial stroke preventive medication after stroke is effective in avoiding a recurrence. Hemorrhagic stroke, heart disease, hypertension, and diabetes increase the likelihood of a recurrence.